{"id":"CVE-2026-33241","aliases":["EUVD-2026-14638","GHSA-pp9r-xg4c-8j4x"],"status":"published","title":"Salvo Affected by Denial of Service via Unbounded Memory Allocation in Form Data Parsing","description":"Salvo is a Rust web framework. Prior to version 0.89.3, Salvo's form data parsing implementations (`form_data()` method and `Extractible` macro) do not enforce payload size limits before reading request bodies into memory. This allows attackers to cause Out-of-Memory (OOM) conditions by sending extremely large payloads, leading to service crashes and denial of service. Version 0.89.3 contains a patch.","severity":{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00454,"percentile":0.39718,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-770"],"published":"2026-03-19T12:44:56Z","modified":"2026-10-28T02:30:44Z","fixes":[{"ecosystem":"crates.io","package":"salvo","fixed_in":["0.89.3"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"crates.io","package":"salvo","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.89.3"}]}]},{"source":"osv","ecosystem":"crates.io","package":"salvo","ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.89.3"}]}]}],"products":[{"vendor":"salvo","product":"salvo"},{"vendor":"salvo-rs","product":"salvo"}],"references":[{"url":"https://github.com/salvo-rs/salvo/security/advisories/GHSA-pp9r-xg4c-8j4x","tags":["x_refsource_CONFIRM","Exploit","Vendor Advisory","advisory","web"]},{"url":"https://github.com/salvo-rs/salvo/releases/tag/v0.89.3","tags":["x_refsource_MISC","Patch","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-33241","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-pp9r-xg4c-8j4x"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33241.json","tags":["advisory"]},{"url":"https://github.com/salvo-rs/salvo","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-33241","title":"Salvo Affected by Denial of Service via Unbounded Memory Allocation in Form Data Parsing","description":"Salvo is a Rust web framework. Prior to version 0.89.3, Salvo's form data parsing implementations (`form_data()` method and `Extractible` macro) do not enforce payload size limits before reading request bodies into memory. This allows attackers to cause Out-of-Memory (OOM) conditions by sending extremely large payloads, leading to service crashes and denial of service. Version 0.89.3 contains a patch.","status":"published","published":"2026-03-23T23:41:50.533Z","modified":"2026-03-25T19:22:48.083Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:20:07.609948Z"}],"euvd":[{"id":"EUVD-2026-14638","description":"Salvo is a Rust web framework. Prior to version 0.89.3, Salvo's form data parsing implementations (`form_data()` method and `Extractible` macro) do not enforce payload size limits before reading request bodies into memory. This allows attackers to cause Out-of-Memory (OOM) conditions by sending extremely large payloads, leading to service crashes and denial of service. Version 0.89.3 contains a patch.","status":"published","published":"2026-03-23T23:41:50Z","modified":"2026-03-25T19:22:48Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T19:25:28.569748Z"}],"ghsa":[{"id":"GHSA-pp9r-xg4c-8j4x","title":"Salvo Affected by Denial of Service via Unbounded Memory Allocation in Form Data Parsing","description":"## Summary\nSalvo's form data parsing implementations (`form_data()` method and `Extractible` macro) do not enforce payload size limits before reading request bodies into memory. This allows attackers to cause Out-of-Memory (OOM) conditions by sending extremely large payloads, leading to service crashes and denial of service.\n\n## Details\n### Vulnerability Description\nThree attack vectors exist in Salvo's form handling:\n\n1. **URL-encoded form data** (`application/x-www-form-urlencoded`)\n   - `Request::form_data()` calls `BodyExt::collect(body)` which reads the entire body into memory without size checking\n   - Affects handlers using `req.form_data().await` directly\n\n2. **Multipart form data** (`multipart/form-data`)\n   - Similar unbounded memory allocation during parsing\n   - Affects handlers processing multipart uploads\n\n3. **Extractible macro**\n   - `#[derive(Extractible)]` with `#[salvo(extract(default_source(from = \"body\")))]` internally calls `form_data()`\n   - Vulnerabilities propagate to all extractors using body sources\n\n### Root Cause\nThe `FormData::read()` implementation prioritizes convenience over safety by reading entire request bodies before validation. Even when `Request::payload_with_max_size()` is available, it's not automatically applied in the form parsing path.\n\n### PoC\n1. run `Extract data from request` example in readme.md in docker file with limited memory say 100mb.\n2. Send `application/x-www-form-urlencoded` OR `multipart/form-data` payload to the endpoint.\n3. The server process OOM-crashes, instead of returning 413 error.\n\n\n## Impact\n### Immediate Effects\n- **Service Unavailability**: Servers crash under memory pressure\n- **Resource Exhaustion**: Single request can consume all available memory\n- **Cascading Failures**: In containerized environments, OOM can affect other services\n\n### Attack Characteristics\n- **Low Cost**: Attacker needs minimal bandwidth (header only, body can be streamed)\n- **No Authentication**: Exploitable on public endpoints\n- **Difficult to Rate-Limit**: Traditional rate limiting may not prevent single large request\n- **Amplification**: Small network cost → large memory consumption\n\n### Real-World Scenarios\n1. Public API endpoints accepting form data\n2. User registration/profile update handlers\n3. File upload endpoints using multipart forms\n4. Any endpoint using `#[derive(Extractible)]` with body sources\n\n## Suggestion: Make Multipart File Upload Handling Explicit Opt-In\n\n### Problem Statement\n\nCurrently, Salvo's multipart form data parsing automatically handles file uploads without explicit developer intent. This creates several security and usability concerns:\n\n1. **Unintended File Storage**: Developers may unknowingly accept file uploads when they only intended to handle text fields\n2. **Disk Space Exhaustion**: Automatic file buffering to disk can fill storage without proper limits\n3. **Resource Cleanup**: Temporary files may not be properly cleaned up if handlers don't expect them\n4. **Attack Surface**: Endpoints inadvertently become file upload targets","status":"published","published":"2026-03-19T12:44:56Z","modified":"2026-03-25T20:48:58Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:39:42.712607Z"}],"nvd":[{"id":"CVE-2026-33241","description":"Salvo is a Rust web framework. Prior to version 0.89.3, Salvo's form data parsing implementations (`form_data()` method and `Extractible` macro) do not enforce payload size limits before reading request bodies into memory. This allows attackers to cause Out-of-Memory (OOM) conditions by sending extremely large payloads, leading to service crashes and denial of service. Version 0.89.3 contains a patch.","status":"published","published":"2026-03-24T00:16:29.517Z","modified":"2026-06-17T10:37:10.61Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":7.5,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","level":"high","assessor":"primary"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T14:12:10.568062Z"}],"osv":[{"id":"CVE-2026-33241","title":"Salvo Affected by Denial of Service via Unbounded Memory Allocation in Form Data Parsing","description":"Salvo is a Rust web framework. Prior to version 0.89.3, Salvo's form data parsing implementations (`form_data()` method and `Extractible` macro) do not enforce payload size limits before reading request bodies into memory. This allows attackers to cause Out-of-Memory (OOM) conditions by sending extremely large payloads, leading to service crashes and denial of service. Version 0.89.3 contains a patch.","status":"published","published":"2026-03-23T23:41:50.533Z","modified":"2026-10-28T02:30:44.699793393Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:45:01.548715Z"},{"id":"GHSA-pp9r-xg4c-8j4x","title":"Salvo Affected by Denial of Service via Unbounded Memory Allocation in Form Data Parsing","description":"## Summary\nSalvo's form data parsing implementations (`form_data()` method and `Extractible` macro) do not enforce payload size limits before reading request bodies into memory. This allows attackers to cause Out-of-Memory (OOM) conditions by sending extremely large payloads, leading to service crashes and denial of service.\n\n## Details\n### Vulnerability Description\nThree attack vectors exist in Salvo's form handling:\n\n1. **URL-encoded form data** (`application/x-www-form-urlencoded`)\n   - `Request::form_data()` calls `BodyExt::collect(body)` which reads the entire body into memory without size checking\n   - Affects handlers using `req.form_data().await` directly\n\n2. **Multipart form data** (`multipart/form-data`)\n   - Similar unbounded memory allocation during parsing\n   - Affects handlers processing multipart uploads\n\n3. **Extractible macro**\n   - `#[derive(Extractible)]` with `#[salvo(extract(default_source(from = \"body\")))]` internally calls `form_data()`\n   - Vulnerabilities propagate to all extractors using body sources\n\n### Root Cause\nThe `FormData::read()` implementation prioritizes convenience over safety by reading entire request bodies before validation. Even when `Request::payload_with_max_size()` is available, it's not automatically applied in the form parsing path.\n\n### PoC\n1. run `Extract data from request` example in readme.md in docker file with limited memory say 100mb.\n2. Send `application/x-www-form-urlencoded` OR `multipart/form-data` payload to the endpoint.\n3. The server process OOM-crashes, instead of returning 413 error.\n\n\n## Impact\n### Immediate Effects\n- **Service Unavailability**: Servers crash under memory pressure\n- **Resource Exhaustion**: Single request can consume all available memory\n- **Cascading Failures**: In containerized environments, OOM can affect other services\n\n### Attack Characteristics\n- **Low Cost**: Attacker needs minimal bandwidth (header only, body can be streamed)\n- **No Authentication**: Exploitable on public endpoints\n- **Difficult to Rate-Limit**: Traditional rate limiting may not prevent single large request\n- **Amplification**: Small network cost → large memory consumption\n\n### Real-World Scenarios\n1. Public API endpoints accepting form data\n2. User registration/profile update handlers\n3. File upload endpoints using multipart forms\n4. Any endpoint using `#[derive(Extractible)]` with body sources\n\n## Suggestion: Make Multipart File Upload Handling Explicit Opt-In\n\n### Problem Statement\n\nCurrently, Salvo's multipart form data parsing automatically handles file uploads without explicit developer intent. This creates several security and usability concerns:\n\n1. **Unintended File Storage**: Developers may unknowingly accept file uploads when they only intended to handle text fields\n2. **Disk Space Exhaustion**: Automatic file buffering to disk can fill storage without proper limits\n3. **Resource Cleanup**: Temporary files may not be properly cleaned up if handlers don't expect them\n4. **Attack Surface**: Endpoints inadvertently become file upload targets","status":"published","published":"2026-03-19T12:44:56Z","modified":"2026-03-25T21:04:54.06903Z","cvss":[{"version":"4.0","score":8.7,"vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-770"],"updated_at":"2026-11-02T15:46:53.244788Z"}]}}